Reef or sea, South Africa
The Sardine Run coast
South Africa's Wild Coast, where shoals of sardines move north each winter, followed by sharks, dolphins and gannets.
Between about May and July, shoals of sardines move north along South Africa's east coast, from the cool waters of the Agulhas Bank towards KwaZulu-Natal, following a band of cooler water close to shore. Predators gather in large numbers, and the Sardine Run off the Wild Coast near Port St Johns has become one of the best-known wildlife events at sea.
Bait balls
Common dolphins herd the sardines into tight bait balls near the surface. Copper sharks, also called bronze whalers, and dusky sharks charge through them, Cape gannets dive from the air, and Bryde's whales sometimes swallow whole balls at once. Divers and film crews come to watch. When the shoals reach KwaZulu-Natal beaches, people wade in to catch them by the bucketful with nets.
A shifting event
The size and timing of the run vary a great deal from year to year, and in some years few sardines come close to shore. Scientists think the run happens when cold water is present along the coast, letting the sardines move north outside their usual range. Shark nets off KwaZulu-Natal beaches are often lifted during the run to reduce the number of sharks and dolphins caught.
Still to be written: Sardinops, Copper shark, Dusky shark, Bluefish.